In partially premixed combustion of gas turbine, the combustion temperature should be lowed in order to reduce NOx. One solution is lean premixed combustion. However, the problem is that large excess air ratio may mak...
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In partially premixed combustion of gas turbine, the combustion temperature should be lowed in order to reduce NOx. One solution is lean premixed combustion. However, the problem is that large excess air ratio may make the combustion unstable. A novel combustor with circumferential reverse flow of fuel gas is proposed for settling this problem. A 10 kw furnace is established to test performance of this combustor. Three factors such as primary air ratio, position of secondary air, total excess air ratio are studied. The emission characteristics and axial flame temperature distribution are studied. Basing on experimental results, the axial flame temperature and NOr emission increase with primary air ratio and axial length of second stream, and decrease with total excess air ratio. When the total excess air ratio is larger than 1.05, the combustor presents a lower temperature field and much lower NOx emission （less than 10 ppm）.
Evaporating falling film on horizontal tubes has been widely used in desalinization, refrigeration, chemical process industries, and so on. In this paper, the flow characteristics of falling film outside horizontal tu...
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Evaporating falling film on horizontal tubes has been widely used in desalinization, refrigeration, chemical process industries, and so on. In this paper, the flow characteristics of falling film outside horizontal tubes in horizontal air flows was studied theoretically and experimentally. Two low patterns of the falling film, i.e., droplet flow pattern and columnar flow pattern, were considered. Effects of the velocity of airflow, the flux of falling film flow, the external diameter of tube and the surface property of tube on the falling film flowing characters were investigated. Experimental study indicated that, in a definite flow scale, as the flow increased, the diameters of falling droplets and falling columns of the liquid enlarged, and the liquid film became thick and the area covered by the liquid film increased. As the air velocity increased, the offset of the droplet and the column to the top of the tube enlarged, and the rate of increase come down until it complete depart from the the top of the horizontal tube. Besides, a theoretical model was established about the offset of the droplet and liquid column from the top of the tube under the force of the horizontal air flows, and the model was validated by a comparison between the numerical predictions and experimental data.A further analysis about the excursion law of falling film flow outside horizontal tube was also made at the last paprt of the paper. [ABSTRACT FROM AUTHOR]
This paper experimentally studied the performance of exhaust steam reclaim device with a swirling flow vane at different inlet water pressures, temperatures, different inlet steam pressures and different distances bet...
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This paper experimentally studied the performance of exhaust steam reclaim device with a swirling flow vane at different inlet water pressures, temperatures, different inlet steam pressures and different distances between the throat and spout. The results indicated that the injection coefficient decreased as the inlet water pressure and temperature increased, respectively. There is a best distance between the throat and spout which makes the injection coefficient reached to its maximal value at the same experimental pressure and temperature, and the value equals to 130 mm in our experimental system. The resistance coefficient has a minimum value which makes the device have the highest outlet water pressure. Compared with the device without a swirling flow vane, it improves the heating performance for higher injection coefficient and exergy efficiency. [ABSTRACT FROM AUTHOR]
An experimental study has been performed to investigate pool water flash evaporation in a rectangle chamber. The water level was at 40 mm, 60 mm, 100 mm, and 150 mm. Initial conditions of the liquid varied from 36 to ...
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An experimental study has been performed to investigate pool water flash evaporation in a rectangle chamber. The water level was at 40 mm, 60 mm, 100 mm, and 150 mm. Initial conditions of the liquid varied from 36 to 88° C temperature and 2.1 to 48° C superheat. The experimental results showed that the initial water temperature, the superheat and the water level are significant to the water temperature transients in flashing process and the value of NEF when flash evaporation calm down. Experimental study allows us to correlate the evolution of water temperature. [ABSTRACT FROM AUTHOR]
In an attempt to understand the problem of severe slagging in biomass-fired boilers, slags formed on the fourth-, second-, and first-stage superheaters in a 12 MW biomass-fired grate furnace have been collected, sampl...
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Aeration is an important factor affecting the biological aeration *** a set of experiment device specially designed for the purpose,and the particle image velocimetry technique,the velocity field of the gas-liquid two...
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Aeration is an important factor affecting the biological aeration *** a set of experiment device specially designed for the purpose,and the particle image velocimetry technique,the velocity field of the gas-liquid two-phase flow is studied under different *** various simulated aeration states were actually applied to the experimental device of sewage treatment,and the results of the numerical simulation were *** final experimental results indicate that the most efficient state occurs when the ratio of water in aeration tank h / w =1,the diameter of capillary tubes d=0.6mm and the velocity of bubbles v=0.3m/s.
Exergy analysis of solar dynamic closed Brayton cycle (SDCBC) for space applications was presented in this paper. An integrated model for the system and specific models for its components were proposed. Influence of m...
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Exergy analysis of solar dynamic closed Brayton cycle (SDCBC) for space applications was presented in this paper. An integrated model for the system and specific models for its components were proposed. Influence of main parameters on system exergy efficiency was discussed. The results shown the efficiencies of expander, compressor, and regenerating temperature of the regenerator have significant influence on the exergy efficiency of SDCBC system. Therefore, besides the enhancement of component efficiencies, the matching among components of SDCBC system should be also taken into account. Moreover, it would be always desirable to enhance the effectiveness of recuperator within the requirements of flow resistance and system weight.
Applying a three-dimensional two-fluid model coupled with homogeneous MUSIG approach, numerical simulations of subcooled water at low pressure were performed on the computational fluid dynamics code CFX-10 with user d...
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Applying a three-dimensional two-fluid model coupled with homogeneous MUSIG approach, numerical simulations of subcooled water at low pressure were performed on the computational fluid dynamics code CFX-10 with user defined FORTRAN program. A modified bubble departure diameter correlation based on the Unal semi-mechanism model was developed. The water boiling flow experiments at low pressure in vertical concentric annulus from reference were used to validate the models. Good quantitative agreement with the experimental data is obtained, including the local distribution of bubble diameter, void fraction, axial liquid and vapor velocity. The results indicate that local bubble diameter first increases and then decreases due to the effect of bubble breakup and coalescence, and has the maximum bubble diameter along the radial direction. Moreover, the peak void fraction phenomenon in the vicinity of the heated wall is predicted at low pressure, which is developed due to the surface tension between vapor bubbles and heated wall. [ABSTRACT FROM AUTHOR]
In this paper a mathematical model is built for a buried hot crude oil pipeline during shutdown, and an unstructured grid and polar coordinate grid are respectively applied to generating grids for the soil region and ...
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In this paper a mathematical model is built for a buried hot crude oil pipeline during shutdown, and an unstructured grid and polar coordinate grid are respectively applied to generating grids for the soil region and the three layers in the pipe （wax layer, pipe wall, and corrosion-inhibiting coating）. The governing equations are discretized using the finite volume method. The variations in temperatures of static oil and soil were investigated during pipeline shutdown in both summer and winter, in which some important parameters of the soil and crude oils of a Northeast pipeline are employed.
A new baffle structure design named open-cell metal foams baffle for anti-sloshing device in oil tank is presented in this study. Numerical simulation study on the liquid sloshing with various baffles is carried out u...
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A new baffle structure design named open-cell metal foams baffle for anti-sloshing device in oil tank is presented in this study. Numerical simulation study on the liquid sloshing with various baffles is carried out using FLUENT with the volume-of-fluid (VOF) model. Four types of baffles were studied, namely non-baffle (type A), conventional parallel-baffle (type B), cross-baffle (type C) and open- cell metal foams baffles (type D). The oil velocity distribution, centroid and oil occupancy in the sloshing process is revealed in the case of vehicle speeding up and turning respectively. It is found that type D reduce velocity of oil, increase the value of oil occupancy in the suction pipe entrance of the oil tank and lower the centroid of oil obviously comparing with the other types. As for the same open-cell metal foam pore density, lower open-cell metal foam porosity has much better effect of inhibition of liquid sloshing, but there is little deviation among different porosity for the absolute value. Moreover, according to the same porosity, the oil centroid can be lowered obviously with the increase of pore density. The results of type D show practical significance and referable guideline for baffles design to improve the safety and stability of vehicle. [ABSTRACT FROM AUTHOR]
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